The 2002 Dirac Medal is awarded to Alan Guth, Andrei Linde and
Paul Steinhardt for the development of the concept of inflation in
cosmology. Although the history of the very early universe has not
been firmly established, the idea of inflation has already had
notable observational successes, and it has become the paradigm for
fundamental studies in cosmology.

While the possibility of an exponential expansion of the early
universe had been noted before, it was Guth who realized that
inflation would solve some of the major problems confronting the
big bang cosmology. Difficulties with the original inflationary
model were recognized by Guth and others, and were overcome with
the introduction of "new" inflation by Linde and Steinhardt (with
Albrecht). Linde went on to propose other promising versions of
inflationary theory, such as chaotic inflation. The greatest
success of inflationary theory has been in accounting for the
existence of inhomogeneities in the universe and predicting their
spectrum, done by Guth (with Pi), Steinhardt (with Bardeen and
Turner), as well as Hawking and Starobinsky.